LM3886 amplifier board gainclone LM3886TF PCB


LM3886 amplifier board gainclone LM3886TF PCB, LM3886 updated with PCB layout, this circuit is a high-quality audio amplifier using integrated circuit for up to 68 Watts of power.

This IC is an integrated circuit that is widely used in audio amplifier designs, so it can be found more easily.
Note that the circuit should be fed from a well-filtered symmetrical source of +34 and -34 volts. L1 is 10 ohms/ 2watt resistor wound with 10 to 12 coils of AWG 20 enameled wire. The lm3886 integrated circuit is an easy component to find in electronics stores, so it is used in many power audio projects, there are some circuits with the IC bridged for power up to 150 watts. For more information about the assembly of this circuit, I suggest you look at the datasheet of the integrated circuit on the Texas Instruments website. With the information in the datasheet (PDF datasheet) you can adapt the circuit with lm3886 to your needs.

The LM3886 is a high-performance audio power amplifier capable of delivering 68W of continuous average power to a 4 Ω load and 38W into 8 Ω with 0.1% THD+N from 20Hz–20kHz.

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The performance of the LM3886, utilizing its Self Peak Instantaneous Temperature (°Ke) (SPiKe) protection circuitry, puts it in a class above discrete and hybrid amplifiers by providing an inherently, dynamically protected Safe Operating Area (SOA). SPiKe protection means that these parts are completely safeguarded at the output against overvoltage, under voltage, overloads, including shorts to the supplies, thermal runaway, and instantaneous temperature peaks.

The LM3886 maintains an excellent signal-to-noise ratio of greater than 92dB with a typical low noise floor of 2.0µV. It exhibits extremely low THD+N values of 0.03% at the rated output into the rated load over the audio spectrum, and provides excellent linearity with an IMD (SMPTE) typical rating of 0.004%.

Lm3886 Pinout Datasheet
Lm3886 Pinout Datasheet

There is an Excel spreadsheet to assist in calculations for amplifiers with LM1876, LM4765, LM4766, LM4700, LM4701, LM2876, LM3875, LM3876 and LM3886:
Overture Design Guide xls
Using the Overture Design Guide

C5 serves to block any DC voltage at the amplifier input and coupling the audio signal, also in conjunction with R5, forms a high-pass RC filter, the formula is Fc=1/2ΠRC. In our circuit it will give 3.2 Hz.

R1 and C6 form a low-pass filter, to avoid RF signals at the amplifier input. The formula is Fc=1/2ΠRC, in our circuit this value was 723kHz, if you prefer you can change this.

R3 is the feedback resistor and defines the amplifier gain, the formula is Av=1+Rf1/Ri where Rf1 = R3 and Ri = R6, in our case we have a gain of 23VV or 27dB.

R8 and C10 form a low-pass filter in the feefback circuit.

R7 and C9 form the Zobel network, preventing high-frequency oscillation caused by inductive loads.

Resistor R1 together with coil L11 were the Thiele network prevents high-frequency oscillation caused by capacitive loads, such as long cables to the speakers.

The mute circuit has resistor R2, must be calculated using the following formula ⇒ RM ≤ (|VEE| – 2.6V)/I8 being I8 ≥ 0.5 mA. VEE is our negative voltage used.

To use the Excel spreadsheet:
Rf = R3
Ri = R6
Ci = C4
Rb = R4
Rin = R5
Cin = C5

If you use the chip with exposed pad, you must use insulator between the IC case and the heat sink.

Characteristics of this IC

  • 68W Cont. Avg. Output Power into 4 Ω at VCC = ±28V
  • 38W Cont. Avg. Output Power into 8 Ω at VCC = ±28V
  • 50W Cont. Avg. Output Power into 8 Ω at VCC = ±35V
  • 135W Instantaneous Peak Output Power Capability
  • Signal-to-Noise Ratio ≥ 92dB
  • An Input Mute Function
  • Output Protection from a Short to Ground or to the Supplies via Internal Current Limiting Circuitry
  • Output Over-Voltage Protection against Transients from Inductive Loads
  • Supply Under-Voltage Protection, not Allowing Internal Biasing to Occur when |VEE| + |VCC| ≤ 12V, thus Eliminating Turn-On and Turn-Off Transients
  • 11-Lead TO-220 Package
  • Wide Supply Range 20V – 94V

Schematic LM3886 amplifier board gainclone LM3886TF circuit diagram

Schematic Lm3886 Amplifier Board Gainclone Lm3886Tf Circuit Diagram
Schematic Lm3886 Amplifier Board Gainclone Lm3886Tf Circuit Diagram

Suggested printed circuit board “PCB” for mounting the amplifier.

Schematic Lm3886 Amplifier Board Gainclone Lm3886Tf Circuit Diagram
Schematic Lm3886 Amplifier Board Gainclone Lm3886Tf Circuit Diagram
Component Viewer Top Pcb Lm3886 Amplifier Board Gainclone Lm3886T
Component Viewer Top Pcb Lm3886 Amplifier Board Gainclone Lm3886T
Silk Pcb Lm3886 Amplifier Board Gainclone Lm3886T.png
Silk Pcb Lm3886 Amplifier Board Gainclone Lm3886T.png

BOM of material to assemble the audio amplifier

Last Update: 05/08/2021 20:10

Part Valor Description Quantity
C1, C3 470µF a 1000µF/50V Electrolytic Capacitor 2
C2 100µF/50V Electrolytic Capacitor 1
C4 22µF/50V Electrolytic Capacitor 1
C5 2.2µF/63V (225) Electrolytic Capacitor 1
C6 220pF/160V (221) Ceramic Capacitor 1
C7, C8 100nF (104) Ceramic Capacitor 2
C9, C11 100nF (104) Capacitor film 2
C10 47pF/160V (470) Ceramic Capacitor 1
IC1 LM3886T or LM3886TF Ci Audio Amplifier from Texas Instruments 1
Resistors 1/4W
R1 10 Ohms 2W Brown, black, black, gold 1
R2 47k Yellow, violet, orange, gold 1
R3, R5, R8 22k Yellow, violet, orange, gold 3
R4, R6 1k Red, red, orange, gold 2
R7 2.7 ohms 2W Red, violet, gold, gold 1
R9 2.2 ohms Red, violet, gold, gold 1
CN1 IN (Input) Terminal block 2 pin 5.08 mm 1
CN2 POWER (Supply) Terminal block 2 pin 5.08 mm 1
CN3 OUT (Output) Terminal block 2 pin 5.08 mm 1
Solder, Wires, PCB, case, power supply, heat sink for the IC, etc.
Download the files to build the sound amplifier project, pcb in PDF, PNG, PS and GERBER.



Download the Datasheet in PDF and application notes.

Model for simulation


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Xtronic.org blog author. Electronics technician for the technical school of Brasilia - Brazil. Interested in electronics, circuits and technology in general.

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